Up to 75% of antibiotic use in nursing homes is inappropriate. Inappropriate antibiotic use increases the nursing home resident's risk of adverse drug events, Clostridium difficile infection and infection with antibiotic- resistant bacteria, whih may then be spread to others. Results of antibiotic stewardship interventions in nursing homes have been mixed. While multi-component interventions targeting provider knowledge and aspects of the work system influencing prescribing decisions appear to reduce inappropriate antibiotic use in nursing homes, the mechanisms by which these interventions work is unclear. In the absence of this knowledge, successful dissemination of these interventions to other nursing home settings will not be possible. Consequently, there is a critical need for nursing home antibiotic stewardship studies that not only evaluate the impact of interventions on prescribing patterns but also evaluate the mechanisms by which they mediate change. Our long-term goal is to reduce inappropriate antibiotic use in nursing homes. Accordingly, our group has developed a novel antibiotic stewardship intervention that targets provider knowledge as well as important work system factors influencing antibiotic decision-making in nursing homes. The objectives of this particular application are to demonstrate the effectiveness of our antibioti stewardship intervention in nursing homes in two states and develop a resource to facilitate dissemination to other nursing home settings. We will achieve the objectives of this project through three specific aims: 1) tailor the antibiotic stewardship intervention for optimal implementation; 2) assess its impact on antibiotic use in study nursing homes; and 3) use knowledge gained to develop a dissemination toolkit. In the first aim, we will use human factors analyses to identify barriers and facilitators to implementation of the antibiotic stewardship intervention. Components of the intervention will be tailored to overcome these barriers and an implementation package will be developed with structured input from key informants in study nursing homes. In the second aim, the tailored antibiotic stewardship intervention will be implemented in study nursing homes using a quality improvement collaborative approach pioneered at the University of Wisconsin and antibiotic utilization measures will be compared with control facilities. In the third aim, knowledge generated from a mixed-methods assessment of intervention fidelity, sustainability and mechanisms by with the intervention mediates study outcomes will be used to develop a dissemination toolkit. The methods we will used to tailor our intervention and support its implementation (quality improvement collaborative) as well as the rigorous program evaluation we will employ to develop a dissemination toolkit are all innovative aspects of this proposal. The proposed research is significant; because it is expected to result in a multi-faceted intervention that can be exported broadly to effectively reduce improve antibiotic use in facilities, which will, in turn, will reduce C. difficile infections and the emergence and spread of antibiotic resistance in nursing homes and the communities they serve.